DISINFECTION OF RECIRCULATED NUTRIENT SOLUTIONS AND CONSEQUENCES TO THE NON-PATHOGENIC MICROFLORA

Infestation of a gerbera crop (cv.
Shimony) grown in a soilless closed culture system by Phytophthora cryptogea resulted in extensive spread of the disease.
Without disinfection of the circulated nutrient solution, about 30% of the plants were severely infected at crop termination. “Active” (UV) and “passive” (slow sand filtration) disinfection completely prevented disease spread.
The disease severity was not affected by starting the crop with “old” or “new” nutrient solutions.
The ability of an established, possibly suppressive microflora to inhibit zoospore release from infected plants was not significantly affected.
Only weak or no effects of the treatments on the structural or functional diversity of microbial communities in drainage water could be recorded.
The slight differences between treatments seem to be mainly caused by the artificially inoculated “infector”-plants.
In contrast to the treatments, the time of sampling (4 incidents) strongly affected the structural as well as the functional diversity of the microbial communities without showing a clear development over time.

International Symposium on Growing Media and Hydroponics

W. Wohanka, R. Seidel

soilless culture, gerbera, microbial diversity, plate count, BIOLOG, water disinfection, slow filtration, Phytophthora cryptogea

https://doi.org/10.17660/ActaHortic.2004.644.72